1. Field of the Invention
The present invention relates generally to an apparatus for reducing steering effort. More specifically, the present invention relates to an apparatus and method for adjusting a vehicle suspension to reduce the steering effort the driver must exert to keep the vehicle travelling in a straight line.
2. Disclosure Information
Drift refers to the lateral displacement of the vehicle on the road when no effort is applied to the steering wheel by the driver. Pull refers to the steering effort or torque the driver applies to the steering wheel to overcome drift. Drivers mistakenly perceive drift and pull as an indication of misalignment of the suspension. However, drift and pull occur often as a result of a road crown, cross wind and other external factors. Road crown refers to the angle between the horizon and the surface of the road beneath and between the steerable roadwheels. A road with the left hand side higher than the right hand side is referred to as having a positive road crown. A positive road crown will cause a vehicle to drift to the right. Cross wind refers to a wind blowing substantially perpendicular to the line of travel of the vehicle. A cross wind blowing on the left hand side of the vehicle will cause a vehicle to drift to the right. It would be desirable to have a suspension that could be adjusted to reduce the pull due to road crown and other external factors.
U.S. Pat. Nos. 4,050,704, and 4,247,126 disclose the use of height adjustable suspension units to control the sway of a vehicle for flexibility for harvesting crops on steeply graded hillsides without spilling the cargo or loosing traction. One primary object of these systems is to allow independent orientation of the vehicle body, relative to the underlying ground, while maintaining tire to ground contact. Neither of these systems teaches adjusting the height of the suspension units to maintain straight line tracking of the vehicle.
U.S. Pat. No. 2,967,062 also discloses height adjustable suspension units to control the sway or pitch of a vehicle to keep the body of the vehicle level during cornering, accelerating and braking. The system does not teach any mechanism for reducing steering efforts to maintain straight line vehicle tracking.
It would be desirable to provide an apparatus and method that substantially reduces the steering effort a driver must apply to keep a vehicle traveling in a straight line on a straight portion of road.